The innovation relates to a tachograph having a printing device, which has a thermal print head and a support, which can be moved out of the front side of the housing of the tachograph, for reloading a ribbon which forms the stock of printing material, and a feed roller which is actively connected, in a force-fitting manner, to the thermal print head, with the printing material between them and is driven by a drive mechanism.
Tachographs which are not designed for the use of record charts as recording media, but rather in which the driving and working time data are stored in suitably designed bulk memories, require suitable printing devices for documentation in the form of a visually readable document, and these devices have to be arranged inside the tachographs since in a driver""s cab of a commercial vehicle there is not generally enough space for the installation of an independent printer which corresponds with the tachograph.
One of the advantages of these tachographs which record by purely electronic means, namely a higher degree of flexibility in terms of where it is arranged within the area which is still accessible to the driver, if, by contrast to the use of plug-in card-like printing substrates, a printing principle with strip-like or ribbon-like printing material is to be used, is restricted in that it is necessary for the printing device in question to be loaded with the stock of printing material and the starting section of the printing material has to be moved into the printing position. An additional difficulty is that tachographs are generally designed as built-in appliances and are therefore fitted with a flush front wall, meaning that access for reloading the stock of printing material is only possible from the front side, using a drawer or a support which can fold or pivot open on the front side.
Therefore, the object of the present innovation was to arrange the printing device of the generic type in such a manner in a tachograph that the handling operations involved in reloading the printing-material ribbon and moving the starting section of the printing material into the printing position can be carried out relatively easily in all possible installation positions of the tachograph.
The solution to the object is described by claim 1. Further advantageous configurations and exemplary embodiments of the innovation are given in the subclaims.
The decisive advantage which is achieved in all the variant embodiments described with the printing device formed in a tachograph according to the innovation is in particular that, after the ribbon has been inserted into the receptacle provided for this purpose and the receptacle, for example a drawer, has subsequently been closed, the printing material automatically moves into the printing and feed position between the thermal print head and the feed roller, which additionally also serves as an abutment. Beforehand, it is merely necessary to ensure that a sufficiently long starting section or printing material is projecting from or has been pulled off the ribbon. In this arrangement, an important aspect of the solution according to the innovation is that the closure gap or a section of the closure gap between the front panel of the drawer and the front wall of the tachograph, which section is parallel to the feed roller, serves as a guide for the printing material or as an output slot for the printed documents produced, at least one of the outer edges of the output slot expediently being designed as a tear-off edge. In other words, the thermal print head and the feed roller are arranged and associated with one another in such a manner that the closure gap can take over responsibility for guiding the printing material which to be advanced by the feed roller. This guidance is formed as a result of the printing material being interposed when the drawer slides closed. At the same time as the drawer slides closed, the thermal print head and the feed roller are actively connected, and it is possible to precisely secure the position of the feed roller in the printing position by means of a suitable clamping device which is preferably associated with the bearing journals of the feed roller.
The innovation therefore offers the advantage that a ribbon can be inserted into the receptacle provided and the printing material can then be moved into the printing position even without a direct view into or onto the drawer.
A further advantage to be emphasized is that the thermal print head can be arranged so that it is largely protected inside the housing of the tachograph or its front wall and therefore the multiwire electrical connection of the thermal print head does not have to be moved. By contrast, if the drive mechanism which drives the feed roller is assigned as a unit to the drawer, significantly fewer flexible lines are required. Moreover, with this type of arrangement, the gear elements between the driving motor and the feed roller are permanently engaged and the drive mechanism can be encapsulated within the drawer so as to be protected against access. Naturally, if certain drawbacks are accepted, the innovation can also be implemented with the arrangement of thermal print head and feed roller reversed or with an arrangement of the drive mechanism in which it is necessary for the drive connection of the feed roller to be engaged and disengaged.
Furthermore, on account of the spatial arrangement of the printer components, the solution which has been discovered offers improved utilization of space compared to the use of a commercially available printing unit, i.e. the solution is apparatus-specific or apparatus-optimized. Moreover, there is no need for additional provisions for eliminating paper jams. However, the decisive factor is that there is no need for the start of the ribbon to be threaded between thermal print head and feed roller, making direct observation and high levels of care unnecessary.
Further advantages of the innovation will emerge from the descriptions of the individual exemplary embodiments.